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Whiteflies seem to be a particularly severe problem this year because our mild winters have not killed the normal number of over-wintering adults. If you walk past your tomatoes or string beans, you often stir up a cloud of tiny white insects flying erratically in all directions. Yes, they can harm your plants! They suck out plant juices which weaken the plant or they may spread disease from one plant to the next. The plant juices they feed on are converted in their bodies to sugary wastes which are excreted on the host plant. This excretion attracts ants and supports the growth of a black, sooty mold. In severe cases, the sooty mold can cover the leaves, blocking sunlight and reducing photosynthesis.

Control is difficult because at one stage in their life cycle, white flies produce a protective coating which shields their body from harmful sprays. The best method of control is a three-pronged attack. First, go through the garden about dusk with your portable vacuum cleaner (Dustbuster or similar). Bump the plants to disturb the whiteflies and then vacuum as many as possible out of the air. This will reduce the population of breeding adults. Next hang yellow sticky traps about every 4 or 5 feet to attract and capture more of the flying adults. Finally, spray the underside of the leaves with Safer Insect Killing Soap which will suffocate the young in their protective coating as well as any adults which are hit with the spray. The spray procedure should be repeated two more times at three day intervals. This procedure will not eliminate all of the whiteflies but should get them down to a manageable level.

Repeat these procedures as necessary.